Spencer Stone, from left, Anthony Sadler and Alek Skarlatos in a scene from "The 15:17" To Paris." (Warner Bros. Pictures)

Clint Eastwood admires flashpoint heroism, those spontaneous acts in crisis making a difference, saving lives. Sully landing a crippled airliner on the Hudson River, three impromptu heroes taking down a terrorist on The 15:17 to Paris.

Both stories are worthy of movies, yet even a filmmaker like Eastwood can’t overcome the brevity of their truths. Capt. Chesley Sullenberger’s heroic actions took under three minutes, so Sully inflated a routine investigation to antagonistic feature length.

The heroism displayed by three American backpackers on a train also took only a few minutes, but The 15:17 to Paris takes a duller route to feature length. Like many sudden heroes, these lifelong friends led unremarkable lives until fate stepped in. Eastwood is committed to depicting every single unremarkable step along the way.

That miscalculation is compounded by Eastwood casting the real-life trio as themselves, making amateurism understandable but no less numbing. Only the child actors portraying their adolescence with eye-rolling and oversold lines annoy more.

Spencer Stone, Alek Skarlatos and Anthony Sadler grew up in Sacramento, Calif., as mischievous kids bullied and disciplined at school. They liked playing war games, leading to Spencer and Alek joining the military. Spencer and Alek had single mothers; Anthony’s African-American parents are ignored until the finale. None of the young men were particularly successful at what they were doing.

Yet Eastwood presses to connect little things picked up along the way with their reflexive actions in crisis. Spencer learned jiu jitsu that he uses to choke out the gunman, along with how to plug a bullet wound with his thumb. Alek knows how to disarm an automatic weapon. Anthony knows how to escort a young woman off the train.

Those few minutes bring out Eastwood’s instinct for tense violence after more than an hour of bland storytelling then travelogue boredom. Casting familiar faces like Judy Greer, Jenna Fischer and the guy who played Urkel doesn’t make growing up interesting. We don’t need to watch the guys sightseeing in Rome, eating gelato in Venice or shaking booties in Amsterdam except for Eastwood to chew up a few minutes of running time.

The 15:17 to Paris weakly attempts suspense by suggesting the men won’t travel on that fateful train but, seriously, read the title. Dorothy Blyskal’s paint-by-vowel screenplay puts foreshadowing words in people’s mouths that even if spoken in reality sound phony here. The finale is Eastwood at his laziest, allowing news footage to do his job. At least Stone, Skarlatos and Sadler now have the ultimate souvenir of their vacation.